Dubbed 'The Big Spliff' at the time, the original tapes found David Gilmour, Nick Mason and the late Rick Wright -- members of the final incarnation of Pink Floyd -- performing a series of ambient, lyricless songs. Mason referenced them a decade ago in his book 'Inside Out,' saying "we eventually ended up with enough left-over material that we considered releasing it as a second album." He compared the music to that of the Orb, with whom Gilmour later collaborated in 2010.

Durga McBroom-Hudson, a long-time backup singer with Pink Floyd, says she's added vocals to these leftover tracks, as has Gilmour. “The recording did start during 'The Division Bell' sessions -- and yes, it was the side project originally titled ‘The Big Spliff’ that Nick Mason spoke about, which is why there are Richard Wright tracks on it," McBroom-Hudson says, via Facebook. "It was originally to be a completely instrumental recording, but I came in last December and sang on a few tracks."

Both McBroom-Hudson and Pink Floyd recording engineer Andy Jackson, in a separate talk with the Floydian Slip news site, confirm that work has continued ever since on the secret project. Gilmour has expanded on the initially recorded backing vocals and, McBroom-Hudson says, "done a lead [vocal] on at least one of them." Gilmour and Mason have made additional musical contributions, as well. “It is the extrapolation of the ‘Big Spliff’ -- a bunch of jams from ['The Division Bell'] sessions that have had new overdubs done in the last year or so,” Jackson says.

Fans will remember that Pink Floyd played a lengthy, atmospheric track before concerts in support of 'The Division Bell.' It's still unclear, however, if that recording -- heard above -- would be part of 'The Endless River.'

Polly Samson, Gilmour's wife and a lyricist for the post-Roger Waters edition of the band, earlier leaked the album title -- which echoes a line from the last song on 'The Division Bell.' Samson also said the project is set for October release.